Half-Life 2 is both different and familiar. It largely retains what made the first game special - the silent protagonist, the lack of cutscenes (with minor exceptions), the set pieces, the physics-based puzzles, and environmental storytelling.

The game's atmosphere and sound design isn't as "scary" (so to say) in comparison to the first game, but the Earth you find itself in is pretty dystopic and depressing. Seeing the whole game only through Gordon's eyes leaves a lot open to interpretation and while I'm normally not the biggest fan of such things, the antagonist of the story - The Combine, feels better left mysterious.

The level design has its ups and downs, but I felt like it was mostly pretty good.
One of the most atmospheric chapters (we don't go to Ravenholm) felt a little confusing to navigate at times, but was pretty fun overall.
The vehicle controls are janky and while those levels (Highway 17, Water Hazard, etc.) are amongst the longest in the game, they work well enough (most of the time) to be surprisingly pretty fun.
A low point of the levels were the fights with the Combine Gunships and Striders, but luckily, those encounters were only a few.
Luckily though, there were no Xen or On a Rail-like levels.

The physics based engine was admittedly pretty rudimentary, but Valve made the best of it through the puzzles.

The gunplay is sometimes said to be the weakest point of the game, but I didn't have too many problems with it.
Yeah, a lot of enemies don't give much of a reaction when hit and the sound of the weapons themselves feels uneven, while some other have a low ammo capacity. But that also encouraged me to try and switch weapons and use the entire arsenal far more often.

Overall, it has its flaws, but I came out of this game pretty satisfied with how it turned out.